scholarly journals Rationalizing the diverse reactivity of [1.1.1]propellane through sigma-pi-delocalization

2020 ◽  
Author(s):  
Alistair Sterling ◽  
Alexander Durr ◽  
Russell C. Smith ◽  
Edward Anderson ◽  
Fernanda Duarte
Keyword(s):  
Charge Transfer ◽  
Electron Density ◽  
Computational Study ◽  
Unified Framework ◽  
Delocalized Electron ◽  
Materials Research ◽  
Pauli Repulsion ◽  
Opening Up

<p>[1.1.1]Propellane has gained increased attention due to its utility as a precursor to bicyclo[1.1.1]pentanes (BCPs) – motifs of high value in pharmaceutical and materials research – by addition of nucleophiles, radicals and electrophiles across its inter-bridgehead C–C bond. However, the origin of this broad reactivity profile is not well-understood. Here, we present a comprehensive computational study that attributes the omniphilicity of [1.1.1]propellane to a moldable, delocalized electron density, characterized by the mixing of the inter-bridgehead C–C bonding and antibonding orbitals. Reactions with anions and radicals are facilitated by stabilization of the adducts through sigma-pi-delocalization of electron density over the cage, while reactions with cations involve charge transfer that relieves Pauli repulsion inside the cage. These results provide a unified framework to rationalize propellane reactivity, opening up opportunities for the exploration of new chemistry of [1.1.1]propellane and related strained systems. </p>

scholarly journals Rationalizing the diverse reactivity of [1.1.1]propellane through sigma-pi-delocalization

2020 ◽  
Author(s):  
Alistair Sterling ◽  
Alexander Durr ◽  
Russell C. Smith ◽  
Edward Anderson ◽  
Fernanda Duarte
Keyword(s):  
Charge Transfer ◽  
Electron Density ◽  
Computational Study ◽  
Unified Framework ◽  
Delocalized Electron ◽  
Materials Research ◽  
Pauli Repulsion ◽  
Opening Up

<p>[1.1.1]Propellane has gained increased attention due to its utility as a precursor to bicyclo[1.1.1]pentanes (BCPs) – motifs of high value in pharmaceutical and materials research – by addition of nucleophiles, radicals and electrophiles across its inter-bridgehead C–C bond. However, the origin of this broad reactivity profile is not well-understood. Here, we present a comprehensive computational study that attributes the omniphilicity of [1.1.1]propellane to a moldable, delocalized electron density, characterized by the mixing of the inter-bridgehead C–C bonding and antibonding orbitals. Reactions with anions and radicals are facilitated by stabilization of the adducts through sigma-pi-delocalization of electron density over the cage, while reactions with cations involve charge transfer that relieves Pauli repulsion inside the cage. These results provide a unified framework to rationalize propellane reactivity, opening up opportunities for the exploration of new chemistry of [1.1.1]propellane and related strained systems. </p>

Charge Transfer via the Dative N−B Bond and Dihydrogen Contacts. Experimental and Theoretical Electron Density Studies of Four Deltahedral Boranes

2011 ◽  
Vol 115 (8) ◽  
pp. 1385-1395 ◽  
Author(s):  
Stefan Mebs ◽  
Roman Kalinowski ◽  
Simon Grabowsky ◽  
Diana Förster ◽  
Rainer Kickbusch ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Electron Density

Mössbauer Spectroscopy as a Tool for Materials Research

MRS Bulletin ◽  
1986 ◽  
Vol 11 (6) ◽  
pp. 14-17 ◽  
Author(s):  
John G. Stevens
Keyword(s):  
Hyperfine Interaction ◽  
Isomer Shift ◽  
Quadrupole Splitting ◽  
Electron Density ◽  
Gamma Ray ◽  
Hyperfine Interactions ◽  
Structure Information ◽  
Resolution Capability ◽  
Materials Research ◽  
Mössbauer Parameters

In 1958 Rudolph L. Mössbauer reported his discovery of a simple, practical way of observing nuclear gamma ray resonance. One of the remarkable features of the discovery was the high precision with which energy changes can be measured: energy resolutions of one part to 1011 −1013 are possible. With this high resolution capability it is possible to measure hyperfine interactions between the nucleus of an atom and its electronic environment. These interactions affect the line shape which can be described by several experimental Mössbauer parameters. The three primary parameters are the isomer shift (δ), the quadrupole splitting (Δ), and the magnetic hyperfine interaction.The isomer shift, determined by the position of the centroid of a set of lines in a spectrum, is proportional to the electron density at the nucleus. Since only s electrons have a probability of being at the nucleus, it is possible to obtain electronic structure information such as oxidation state and population of certain molecular orbitals.The quadrupole splitting results when the electron environment surrounding the Mössbauer nucleus is not spherical in its charge distribution. Specifically, Δ is proportional to the imbalance in electron density between the axial and equatorial directions. When this hyperfine interaction is present, there is a quadrupole splitting; i.e., a single spectra line will split into two or more lines.

Charge Transfer Complexes of N-Arylcarbamates with π-Acceptors

1987 ◽  
Vol 42 (3) ◽  
pp. 284-288 ◽  
Author(s):  
Aboul-fetouh E. Mourad
Keyword(s):  
Charge Transfer ◽  
Electron Density ◽  
Nmr Spectra ◽  
Charge Transfer Complexes ◽  
H Nmr ◽  
Ct Complexes

The charge-transfer (CT) complexes of some N-arylcarbamates as donors with a number of π-acceptors have been studied spectrophotometrically. The Lewis basicities of the N-arylcarbamates as well as the types of interactions are discussed. The 1H-NMR spectra of some CT complexes with both 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ) and 7,7,8,8 tetracyanoquinodimethane (TCNQ) indicate a decrease of the electron density on the donor part of the complex.

Structural order and charge transfer in highly strained carbon nanobelts

2020 ◽  
Vol 44 (36) ◽  
pp. 15769-15775
Author(s):  
G. Aydın ◽  
O. Koçak ◽  
C. Güleryüz ◽  
I. Yavuz
Keyword(s):  
Charge Transfer ◽  
Closed Loop ◽  
Computational Study ◽  
Structural Order ◽  
Chiral Carbon ◽  
Highly Strained ◽  
Transfer Properties

We present a computational study of the atomic morphology, structural order and charge transfer properties of radially π-conjugated, closed-loop, and highly strained chiral carbon nanobelts (CNBs).

Photoinduced excitation and charge transfer processes of organic dyes with siloxane anchoring groups: a combined spectroscopic and computational study

2017 ◽  
Vol 19 (23) ◽  
pp. 15310-15323 ◽  
Author(s):  
Elena Castellucci ◽  
Marco Monini ◽  
Matteo Bessi ◽  
Alessandro Iagatti ◽  
Laura Bussotti ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Organic Dyes ◽  
Computational Study ◽  
Transfer Processes ◽  
Anchoring Groups

New dyes for DSSCs applications have been characterized.

scholarly journals Characterizing the interplay of Pauli repulsion, electrostatics, dispersion and charge transfer in halogen bonding with energy decomposition analysis

2018 ◽  
Vol 20 (2) ◽  
pp. 905-915 ◽  
Author(s):  
Jonathan Thirman ◽  
Elric Engelage ◽  
Stefan M. Huber ◽  
Martin Head-Gordon
Keyword(s):  
Charge Transfer ◽  
Bond Strength ◽  
Halogen Bond ◽  
Decomposition Analysis ◽  
Halogen Bonding ◽  
Energy Decomposition Analysis ◽  
Energy Decomposition ◽  
Pauli Repulsion

Variational energy decomposition analysis establishes charge-transfer as the origin of halogen bond strength differences that go against electrostatics.

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